Venting the H2D through 4” hose outside - control from printer?

[Minok1217]

The H2D with 40w laser is sitting in the garage. Pacific Northwest here, so temps in the garage in my location are under 70-80f ( 21-27c) tops even in July.

Installed a 4” vent through the wall to the outside, fight next to the printer to keep the hose runs short. Most of it is fixed rigid bends and Y splits. I’ve installed a 6” AC Infinity S6 up near the exit to the outside through the wall to pull air up from the workbench below. My thinking is the 6” fan (using 4-6 reducers of course ) will let me run then fan a bit slower than a 4” fan to keep the airflow at a similar level.

Below the fan the air intake forks to three different 4” ways , each with a blast gate to block it off. The shortest and closest to the fan intake is the one I’m connecting the H2D up to.

To get an idea of the speed to run the S6 at, I got my anemometer out and measure the air speed at the input to the blast gate (without the printer attached ) as well as out of the printer’s rear vent with the Bambu 4” vent pipe collar attached ( but no hose ).

The S6 fan at setting 1/10 pulled 157 ft/min in at the blast gate input.
The H2D blew out 373 ft/min at its 10% setting.

Then at full:
The S6 fan at 10/10 pulled 2105 ft/min at the blast gate input.
The H2D blew 2046 ft/min at its 100% setting.

So the two line up somewhat well in my plumbing arrangement.

So my thinking : tap the PWM control of the H2D fan

, send it out through a galvanically separated optocoupler circuit to the S6 so that the S6 gets set to the same level as the H2D is driving its fan. To be verified with an oscilloscope to check the actual duty cycles etc first.

Question:

Has anyone else done such interfaces between their H2D and an inline fan? If so, I’m interested in lessons learned and best approaches to drive for a good solution to share here.

As an aside , for completeness sake , I then attached the flexible 4” hose that came with the Bambu to the H2D rear fan flange , and with the H2D fan running at 100%, took another measure at the end of that 3-4 foot long flex hose to see how much is lost in drag down that hose. The 100% exit speed at the end of that 4” hose dropped from the 2046 ft/min from the flange direct at the fan exit, down to 1318 ft/min. A good 35% drop.

So with that hose in place I can run the S6 fan less than the 10/10, probably more around 7/10 level to keep the airflow going.

[user_2699860320]

I use Home Assistant, the Bambu Lab HACs community add-in and ESPHome to control the exhaust in my small 12x12 office. I started simply by having the H2S Laser combo use it’s internal fan only, that didn’t work well at all. I then bought a cheap $45 4” inline bower fan, which worked ok, but was loud and I had to turn it up/down manually. I then built my own setup with a 220cfm 120mm fan mounted outside the window in a weatherproof enclosure controlled by Home Assistant matching the H2S exhaust % using Home Assistant automations. This worked well until I added an xTool F1 Ultra to the system and then I pretty much ran the 120mm fan full blast to overcome the extra ducting. Damn was that loud… jet engine loud. Also my office started getting incredibly hot due to the F1 and H2S (printing lots of ASA).

I then figured I need to go big, which I SHOULD HAVE DONE FROM DAY 1. I bought an 800+ cfm 8” VivoSun AeroZesh T8 (essentially an AC Infinity S8). Controlled with an ESPHome device and Home Assistant. at 20% it is silent and outperforms my previous setups easily (even with two 4” ports wide open to the room). Using Home Assistant, a couple ESPHome devices (anemometer and a decibel sensor) and Claude to do the testing, I found that 31% power both cooled my room down and provided significantly more CFM to the H2S and F1 Ultra. While I do have home assistant monitoring the exhaust setup, it runs at 31% all the time, with the only exception being when my room gets hot (>5 degrees higher than the rest of the house) it bumps to 50% until it cools down.

I’m sure you can physically setup the H2D exhaust to control the speed of the S6 with the optocoupler circuit, in the long run you may want more varied control. e.g. Printing ASA, the exhaust of the H2D won’t run, but you may want to have some exhaust to avoid fumes/smells. Using an automation system is one way to get that flexibility.

My physical setup looks very similar to yours. Although I split to 4 x 4” ducts with two open, 1 to H2S and one to my F1 Ultra and have completely removed the blast gates I used to have.

BTW: I’m in PNW (Seattle) too.

[user_2463535618]

I use HA as well to control the exhaust fans for the room as well as the air purifier which has both carbon and the filter, mainly for the filter though. It never triggers on particle detection anymore. I dont use laser but am sensitive to the VOCs so I can tell its working since I dont get irritation anymore. I vent outside and keep my inline fan at the end of the run just before the exit as the vendor states keeping it in the middle or begging can wear the hose out fast.

I have a Y splitter and a damper with a zwave actuation that opens up when the exhaust is closed on the printer, the inlet of the second hose hangs right above the printer back and it does a pretty good job of pulling the fumes out that slip by the poop chute.

[Minok1217]

It is interesting to learn about the various approaches folks go through to address issues like this.
As my printer is in the garage , and I’ve already printed ASA with it just the printer in the garage and no external ducting , and it’s fine. For now, I’m only looking to extract when the H2D also decides to extract ( or independently when one of the two blast gates that come off of the run that disappears behind the printer get used - die my airbrush boot or a mini hood above a resin printer).

Also I want to keep the control closed loop and avoid having to rely on network service in any way.

We are living the good weather life. I’m over in Sammamish.